1. Technical Field
Example embodiments disclosed herein relate to a rotor profile for a screw compressor.
2. Description of the Related Art
Generally, a screw compressor has a female rotor and a male rotor, which are operated in an operation space in a housing. If the female rotor and the male rotor are engaged with each other and rotated, a sealed volume in the housing is reduced by the rotors, and accordingly gas or air is compressed. The efficiency of the screw compressor is mainly dependent on processing precision and shape of the rotors. At present, many studies are under progress to improve a rotor profile which determines a geometric shape of the rotor.
Once, a rotor having a symmetric profile was used, but the rotor profile has changed into an asymmetric shape so as to minimize a leakage triangle and enhance insulation performance. So, curves configuring such a profile tend to be very complicated.
Factors giving bad influences on the efficiency of a screw compressor, caused by a geometric shape of the rotor profile, are increase of a gap between the rotor and the housing, increase of a gap between rotors in such as a vacuum-forming space, increase of volume of the leakage triangle, and so on.
In order to exclude such factors giving bad influences on the efficiency of a screw compressor as much as possible, there was an attempt to make the vacuum-forming space smaller and reduce a radius of a following-side of the female rotor such that a size of the leakage triangle is decreased. However, at this attempt, an actual tool of the rotor has a decreased pressure angle, so a machining error is increased during a machining process and also precise machining of the rotor becomes difficult. This problem results in deteriorated quality of the compressor.
Slip phenomenon occurring at a contact point by the geometric shape of the rotor profile when the rotors are operated is another factor to decrease the efficiency of a screw compressor. If a slip occurs at a contact point when the rotors are operated, the rotors scratch each other, which wears the rotors easily and increases noise of the compressor.